RÉSUMÉ
Background/Aims@#To evaluate the efficacy of quadruple-coated probiotics (gQlab) in patients with irritable bowel syndrome (IBS), focusing on sex differences and IBS subtypes. @*Methods@#One hundred and nine Rome III-diagnosed IBS patients were randomized into either a gQlab or placebo group and received either gQlab or a placebo for 4 weeks. Participants replied to questionnaires assessing compliance, symptoms, and safety. Fecal samples were collected at 0 and 4 weeks to measure the probiotic levels using real-time quantitative polymerase chain reaction (qPCR) and to perform metagenomic analysis via 16S ribosomal DNA sequencing. The primary endpoint was the change in the overall IBS symptoms after 4 weeks of treatment. @*Results@#Ninety-two subjects (47 and 45 in the gQlab and placebo groups, respectively) completed the study protocol. At week 4, there was a higher relief of the overall IBS symptoms in the gQlab group (P = 0.005). The overall IBS symptom improvement was statistically significant (P = 0.017) in female patients of the gQlab group compared with the placebo group. Among the IBS subtypes, constipation-predominant IBS patients showed significant relief of the overall IBS symptoms (P = 0.002). At week 4, the fecal microbiome profiles between the 2 groups did not differ, but the qPCR levels of Lactobacillus plantarum, Lactobacillus acidophilus, Lactobacillus helveticus, Bifidobacterium longum, and Bifidobacterium breve were increased in the gQlab group (P < 0.05 by repeated measures ANOVA). @*Conclusions@#gQlab administration can improve the overall IBS symptoms, especially in female and constipation-predominant IBS patients. Further research is necessary to clarify the pathophysiology behind sex-related treatment responses in IBS patients.